They'll run just fine on 95 or less probably, but you need super to get to the best from such a high revving engine.

Smoothness aside, on a N/A engine it will suffer at all revs, but more so above 6krpm with 95 ron because the ECU can't maintain the kind of ignition advance really required to operate efficiently above that speed without detonation, so it has to use less ignition advance, thus the torque will tail more rapidly, reducing power output at all revs but more so higher up of course.

This is even more so in a 335i, where evolve have dyno'd differences of 40bhp between 95ron and Vmax99